(E)-1-[1-(4-Chlorophenyl)ethylidene]thiosemicarbazide

In the crystal structure of the title compound, C9H10ClN3S, the molecules form chains parallel to [001] through N—H⋯S hydrogen bonds. In addition, weak intermolecular N—H⋯Cl hydrogen bonds connect the chains, forming a two-dimensional network parallel to (001).

In the crystal structure of the title compound, C 9 H 10 ClN 3 S, the molecules form chains parallel to [001] through N-HÁ Á ÁS hydrogen bonds. In addition, weak intermolecular N-HÁ Á ÁCl hydrogen bonds connect the chains, forming a two-dimensional network parallel to (001).

Experimental
A solution of 1-(4-chlorophenyl)ethanone (3.092 g 0.02 mol) and thiosemicarbazide (1.82 g, 0.02 mol) in absolute methanol (80 mL) was refluxed for 2 h in the presence of p-toluenesulfonic acid as catalyst, with continuous stirring. On cooling to room temperature the precipitate was filtered off, washed with copious cold methanol and dried in air.
Colourless single crystals of compound (I) were obtained after recrystallisation from a solution in methanol.

Refinement
All H atoms located at the difference Fourier maps and isotropically refined. At the end of the refinement the highest peak in the electron density was 0.310 eÅ -3 , while the deepest hole was -0.300 eÅ -3 .

Figure 1
A view of the molecular structure of the title molecule showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
The principal differences of para-isomer (I) and ortho-isomer (II).  H atoms not involved in hydrogen bonding have been omitted for clarity. Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.